Short version:
Is any green coolant OK to mix with the green coolant currently in my car? Even when I'm going to store it fore another 3 months before I can flush the coolant or drive it again?

Details
it's been a while, my car has been in the garage since november.
I pulled it out and was about to start it up and notices in my inspection that the coolant cap (the one coming off the engine, was dry)

I don't want to put the wrong type of coolant in because I've heard that it can combine with the stuff thats currently in there and become corrosive. Currently, I have the green stuff in there (I will confess its from the previous owner, its going to get flushed when i get back in the summer).

What sort of coolant should I put in there before I start her up. I don't have time to do a flush before I store the car until May. And I need to get my emissions test done before I leave. (It's due in april). Please advise. I've done the search, but I want to be sure.

 

how much is missing? you can add water unless it is completely dry

 

Yes, get the green stuff. I use standard any-color prestone or the generic versions of it.

 

thanks,
and I don't know how much is missing, I can't see any coolant from the cap.

 

Don't mix green and orange and you'll be ok.

Just pore DISTILLED water or the green **** in and go for it. Make sure that you bleed it correctly so the low water level alarm doesn't go off. I'm sure that's written up here somewhere.